The broad objective of this research is to help understand the underlying mechanisms of viral tumorigenesis and related genetic processes. Papovaviruses and adenoviruses are being characterized at a molecular level, including the genetic organization of these viruses, function of transforming genes and proteins, and viral DNA replication: SV40 is also being used as a vector for recombinant DNA. Among the related cellular processes being studied are recognition of nucleotide sequences by DNA restriction and modification enzymes, the enzymology of DNA repair, and recombination between cellular and viral DNA.